A  PORE  WATER  SUPPLY  FOR 


BY  G.  BOUSCAREN. 


A  Paper  Read  before  the  Engineers  Club  of 
Cincinnati,  April  18,  1895. 


The  sources  of  water  supplies  for  towns  and  cities  may  be 
classified  under  the  headings  of  Lakes  and  Impounding  Reservoirs, 
Springs,  Underground  Water  and  Water  Courses. 

All  these  waters  have  a  common  origin  and  come  to  us  as 
distilled  water  from  the  clouds,  but  this  initial  purity  becomes 
impaired  from  the  instant  of  condensation.  The  rain-water 
reaches  the  surface  already  impregnated  with  dissolved  gases,  and 
with  a  variety  of  minute  debris  and  germs  which  compose  the 
floating  dust  ever  present  in  the  atmosphere. 

As  it  washes  over  the  surface  or  penetrates  into  the  soil,  this 
water  becomes  farther  charged  with  earthy  and  organic  matter, 
and,  it  may  be  truly  said,  that  absolutely  pure  water  in  the  liquid 
state  does  not  exist  in  nature.  This  fact  should  be  borne  in  mind 
when  speaking  of  the  purity  of  water  in  connection  with  water 
supplies.  Purity ,  in  this  sense,  meaning  simply  absence  of 
elements  injurious  to  health,  or  harmful  to  purposes  for  which 
water  is  used.  It  may  indeed  be  surmised  from  the  same  fact, 
that  water  chemically  pure  is  not  necessary  or  even  desirable  for 
human  consumption,  except  as  a  compounding  ingredient  of 
physicians’  prescriptions. 

Limpidity  and  freedom  from  an  excess  of  the  mineral  salts 
which  constitute  what  is  commonly  called  Hardness ,  are  essen¬ 
tial  requisites  in  water  used  for  cooking  and  washing  and  for  cer¬ 
tain  processes  of  manufacture.  For  this  reason  physical  purity 
and  softness  have  always  been  considered  of  great  importance,  and 
until  25  or  80  years  ago,  the  only  qualities  required  for  potable 
water.  Contamination  by  sewage  was  considered  injurious  to 


<U  i.  VV 

M 


_ 2 _ 

health,  and  an  abnormal  proportion  of  organic  matter  objectiona¬ 
ble,  as  a  probable  indication  of  such  contamination.  The  presence 
of  infusoria  and  other  small  animalcula  in  water  had  long  been 
known  ;  but  seems  to  have  been  considered  as  a  necessary  evil  of 
no  great  concern,  as  long  as  the  diminutive  size  of  the  creatures 
kept  them  hidden  from  view. 

The  discoveries  of  Pasteur  and  Koch,  which  laid  the  founda¬ 
tion  for  the  modern  theory  of  germs  in  Pathology,  sounded  the 
first  alarm  by  revealing  the  danger  lying  in  the  omnipresence  of 
Bacterial  life,  and  the  researches  of  their  numerous  followers  have 
established,  beyond  reasonable  doubt,  positive  evidences  of  the 
indentation  of  cholera  and  typhoid  fever  through  drinking  water. 
^  The  character  of  a  water  supply  should  therefore  be  considered 
under  three  distinct  aspects :  Physical,  Chemical  and  Biological. 
In  the  light  of  modern  investigations  the  latter  would  seem  to  be 
by  far  the  most  important  of  the  three,  as  regards  their  possible 
influence  on  human  health,  and  Bacteriological  examinations  are 
now  an  indispensable  adjunct  to  water  works  and  sanitary 
engineering. 

Dr.  Percy  Frankland  in  his  treatise  on  “  Micro-organisms  in 
Water"  gives  a  list  of  152  species  of  Bacilli  and  of  43  Micrococci 
which  have  been  observed  in  water.  These  lists  are  probably  in¬ 
complete,  as  new  forms  are  being  constantly  discovered.  Fortun¬ 
ately  23  only  of  these  species  are  known  or  suspected  to  be 
pathogenic  to  man  and  animals,  and  their  occurrence  is  rare  as 
compared  with  that  of  the  harmless  ones. 

Water  collected  from  the  rocky  slopes  of  mountainous  water¬ 
sheds  into  lakes  and  artificial  reservoirs,  is  generally  clear,  soft  and 
wholesome  ;  provided  the  drainage  area  be  uninhabited  and  uncul¬ 
tivated  or  under  perfect  control.  Liverpool  and  Manchester,  New 
York  and  Boston,  are  notable  examples  of  such  supplies.  On  the 
other  hand,  the  presence  of  only  a  few  habitations  on  the  drainage 
area  may  be  a  dangerous  source  of  pollution,  and  surface  water 
from  well  settled  districts  and  cultivated  lands,  is  entirely  unfit 
for  domestic  usage  without  artificial  purification. 

Spring  water,  when  not  charged  with  an  excess  of  mineral 
salts  in  solution,  is  generally  preferred  for  drinking  purposes. 
When  the  water  rises  from  a  deep-seated  source,  as  it  generally 
does  in  perennial  springs,  it  is  practically  free  from  bacteria.  So- 
called  “  wet  weather"  springs,  the  flow  of  which  varies  with  the  sea- 


r 


sons,  should  be  regarded  with  suspicion.  They  are  generally  fed 
by  surface  water  percolating  through  a  thin  stratum  of  porous 
soil.  Many  well  springs  belong  to  that  class. 

Subterranean  waters  tapped  through  an  impervious  stratum 
of  rock  or  clay  are,  as  a  rule,  identical  in  character  with  spring 
water.  Water  courses  derive  their  supply  from  springs  and 
.surface  drainage.  Their  water  partakes  of  the  character  of  both: 
spring  water  predominating  during  periods  of  low  stages,  when 
the  water  is  clear  and  more  heavily  charged  with  minerals;  whilst 
softness  and  turbidity,  as  a  rule,  characterize  the  flood  water. 
Owing  to  the  variety  of  soils  and  formation  traversed  by  large 
rivers,  and  the  blending  of  waters  from  many  subsidiary  streams 
tributary  to  their  flow,  they  should  and  do  afford  excellent  sources 
of  supply  when  fed  by  the  drainage  of  a  sparsely  populated  region 
and  when  not  polluted  by  sewage  ;  even  then,  the  power  of  self¬ 
purification,  aided  by  sedimentation  in  large  settling  basins,  is 
often  sufficient  to  give  reasonably  pure  water,  provided  that  the 
source  of  pollution  be  sufficiently  remote  to  allow  the  process  ot 
self-purification  to  take  place. 

Such  were  the  conditions  generally  prevailing  in  this  country 
before  the  formation  of  the  numerous  centers  of  population  and 
manufacturing  which  have  naturally  gravitated  to  the  lines  oi 
transportation  afforded  by  navigable  rivers.  For  the  time  being, 
many  cities  and  towns  derived  satisfactory  supplies  from  the 
streams  which  carried  their  trade  to  the  ocean,  but  with  the 
rapid  fouling  of  these  streams,  incident  to  the  growth  of  popula- 
lation  and  to  the  practice  of  emptying  untreated  sewage  into 
them,  it  was  only  a  question  of  time  when  the  process  of  self-puri¬ 
fication  would  become  inefficient ;  the  accession  of  organic  matter, 
with  its  hosts  of  bacteria  from  the  sewage  of  the  successive  towns, 
taking  place  faster  than  the  destruction  of  the  same  by  oxidation 
and  other  natural  agencies. 

Such  conditions  now  obtain  for  some  streams  of  the  Atlantic 
slope.  Careful  analyses  of  the  waters  of  the  Passaic  River  at  dif¬ 
ferent  points  on  its  course,  made  by  Dr.  Charles  D.  Currier,  show 
an  increasing  number  of  bacteria  in  the  down  stream  direction. 
Outbreaks  of  typhoid  fever  have  warned  the  people  of  their 
danger,  and  they  are  being  forced  to  seek  purer  supplies  from  the 
mountains  or  from  underground  sources,  or  to  have  recourse  to 
artificial  methods  of  purification. 


—  4  — 


Many  of  the -streams  of  the  Mississippi  basin  are  fast  ap¬ 
proaching  to  the  same  status.  The  Ohio  in  particular,  if  not 
comparable  as  yet  to  the  Passaic  River,  has  ceased  to  be  a  safe 
source  of  supply  at  certain  seasons  of  the  year.  The  recurrence 
of  typhoid  fever  every  year  at  the  end  of  the  period  of  low  water 
stages  is  an  admonition  which  the  city  of  Cincinnati  cannot 
afford  to  ignore.  Louisville  and  St.  Louis  are  leading  us  in  this 
respect.  Although  possessed  of  better  works  than  Cincinnati,  in¬ 
asmuch  as  they  take  their  water  above  all  local  source  of  contami¬ 
nation,  they  are  now  seriously  considering  the  problem  of  artificial 
purification. 

The  first  question  that  presents  itself  is:  Shall  we  adopt 
some  other  source  of  supply,  or  shall  we  abide  by  the  river  and 
purify  its  water  by  proper  treatment  ?  , 

The  geographical  position  of  Cincinnati,  at  the  center  of  a 
thickly  populated  and  agricultural  basin  of  large  area,  is  very 
unfavorable  to  the  application  Of  impounding  reservoirs.  The 
necessary  outlay  to  control  the  drainage  of  such  reservoirs  would 
be  enormous,  and  the  character  of  the  impounded  water,  in  spite 
of  all  precautions,  would  probably  be  such  as  to  require  purifica¬ 
tion. 

Springs  of  adequate  capacity  are  not  within  reach.  The  only 
alternative  to  the  river  is  the  underground  water  flowing  in 
the  drift  formations,  down  the  valleys  of  Millcreek  and  the 
Little  Miami.  Several  suburban  villages  are  now  being  supplied 
from  this  source.  The  water  is  confined  below  a  stratum  of  clay 
and  is  probably  free  from  .surface  contamination.  The  water  from 
the  wells  at  Norwood  contain  26^  solid  in  100,000  parts  ;  about 
one-fourth  of  which  is  sulphates  of  lime  and  magnesia,  and  three- 
fourths  carbonates  of  lime  and  magnesia.  It  must,  therefore,  be 
classed  as  hard  water,  and  would  require  treatment  by  the  lime 
process  for  softening,  but  the  main  question  which  arises  is  that 
of  quantity. 

The  water  in  the  wells  at  Norwood  rises  46  feet  above  its 
plane  of  confinement  under  the  clay,  and  90  feet  above  low  water 
in  the  Ohio  River.  On  the  occasion  of  the  test  made  on  April 
24,  1894,  when  the  deep  well  pumps  were  operated  for  sixteen 
consecutive  hours,  and  a  draught  of  500,000  gallons  made  during 
that  time  from  four  wells,  20  feet  apart,  the  greatest  depression 
observed  in  the  surface  of  water  in  the  wells  was  7  feet  6  inches. 


These  facts  and  conditions  indicate  an  abundant  source  of  supply 
for  the  village,  but  would  not  justify  the  conclusion  that  it  could 
be  depended  upon  permanently  for  a  daily  draught  of  thirty  or 
forty  million  gallons.  Experience  shows  that  the  rate  of  motion 
of  subterranean  waters  through  sand  may  plot  exceed  a  few  feet 
in  twenty-four  hours,  and  that  whilst  a  large  volume  of  water 
may  be  extracted  rapidly  from  a  sand  bed,  a  long  time  may  be 
required  to  replenish  it  from  the  fountain  head.  The  quantity  of 
water  that  can  be  regularly  and  permanently  drawn  from  a  sub¬ 
terranean  bed,  must  therefore  be,  to  a  great  extent,  a  matter  of 
conjecture,  until  tested  through  a  long  period  of  time. 

With  this  element  of  uncertainty  before  him,  I  believe  that 
no  one  with  a  due  regard  to  the  finances  of  the  city  would  be  jus¬ 
tified  in  recommending  the  experiment. 

If  these  premises  are  accepted,  the  conclusion  is  that  we 
must  adhere  to  the  river,  and  the  question  is  :  What  means  should 
be  employed  to  render  its  water  wholesome  at  all  times? 

The  principal  methods  that  have  been  applied  in  America  and 
Europe  for  the  artificial  purification  of  water  supplies;  are  settling- 
reservoirs,  filtering-galleries  or  wells,  aeration,  agitation  with  iron 
scraps,  chemical  treatment:  as  by  Clark’s  lime  process,  mechanical 
filtration  in  closed  vessels,  and  sand  filtration  on  artificially  con¬ 
structed  filter-beds.  A  combination  of  two  or  more  of  these  dif¬ 
ferent  methods  is  also  employed. 

Everyone  knows  that  the  proportion  of  solid  matter  carried 
by  the  water  of  running  streams  bears  a  clo.se  relation  to  the 
rapidity  of  motion.  The  storage  of  water  before  its  distribution, 
in  large  reservoirs  or  pools  where  a  state  of  rest  or  a  sluggish 
current  would  allow  the  suspended  particles  to  drop  to  the  bot¬ 
tom,  suggested  itself  naturally  at  an  early  date,  and  has  been 
extensively  used  as  a  process  of  clarification.  These  reservoirs 
are  indeed  indispensable  features  of  water-work  plants  supplied 
from  muddy  streams,  such  as  the  Ohio,  the  Mississippi,  and  *the 
Missouri  rivers.  Careful  studies  made  in  recent  years  by  Euro¬ 
pean  investigators  have  demonstrated  that  the  effect  of  storage  is 
not  only  to  improve  the  water  in  physical  appearance,  but  in 
chemical  and  biological  character  as  well;  in  reducing  its  contents 
in  organic. matter  and  bacteria. 

Proskauer  found  the  waters  of  the  River  Spree,  which  supplies 
Berlin,  greatly  improved  bacterially  after  its  passage  through 
Havel  lake. 


—  6  — 

Tils  showed  that  the  water  from  the  mountain  stream  which 
supplies  Freiburg  is  similarly  improved  after  subsidence  in  the 
reservoir. 

Dr.  Percy  Frankland’s  experiments  with  London  water  gave 
the  following  results : 

At  the  Grand  Junction  Company’s  works — 

First  specimen  from  the  Thames  at  the  intake,  1,991  bacteria  in 
one  cubic  centimeter. 

Second  specimen  from  first  small  storage  reservoir,  1,703  bacteria 
in  one  cubic  centimeter. 

Third  specimen  from  second  small  storage  reservoir,  1,556  bacteria 
in  one  cubic  centimeter. 

Fourth  specimen  from  large  storage  reservoir,  464  to  368  bacteria 
in  one  cubic  centimeter — 

Showing  a  gradual  decrease  in  the  number  of  bacteria  as  the 
time  of  storage  increased. 

At  the  West  Middlesex  Company’s  works — 

Water  at  intake,  1,437  bacteria. 

Water  after  going  through  two  storage  reservoirs,  177  bacteria. 

At  the  New  River  Company’s  works — 

Water  above  reservoir,  677  bacteria. 

Water  from  outlet  of  second  reservoir,  183  bacteria 

These  beneficial  effects  are  explained  by  the  supposition  that 
the  bacteria  become  attached  to  the  solid  particles  and  are  carried 
with  them  to  the  bottom,  which  is  confirmed  by  the  fact  that  a 
greater  degree  of  purification  is  always  obtained  with  water  con¬ 
taining  a  greater  amount  of  sediment  or  by  the  addition  of  a 
coagulent,  such  as  alum  ;  or  by  chemical  precipitation,  such  as 
takes  place  in  Dr.  Clark’s  lime  process. 

On  the  other  hand,  the  purification  is  at  best  incomplete,  and 
the  time  required  for  the  subsidence  of  the  smaller  particles  may 
be  so  great  as  to  require  reservoirs  of  immense  capacity.  Further-  • 
more,  the  milky  appearance  of  certain  waters  caused  by  the  pres¬ 
ence  of  fine  clay,  and  the  brownish  color  imparted  by  peaty  soils, 
cannot  be  removed  by  sedimentation  of  any  practicable  duration. 

Infiltration  galleries  and  wells  built  in  sand  or  gravel  on  the 
margin  of  rivers  and  lakes  have  also  been  used  for  the  clarification 
of  turbid  water,  sometimes  with  success;  as  at  Perth/Genoa, 
Lyons,  and  Toulouse,  in  Europe,  and  at  Waltham  and  Brookline, 


-  7 


in  Massachusetts.  But  in  a  great  number  of  instances  they  have 
been  a  failure,  owing  to  the  gradual  silting  of  the  filtering 
medium. 

Whilst  the  water  thus  collected  is  generally  clear  and  im¬ 
proved  in  appearance,  it  is  quite  frequently  more  heavily  charged 
with  dissolved  mineral  salts,  and  often  impaired  by  a  strong  taste, 
which  would  indicate  that  a  part  at  least  of  the  water  percolating 
in  the  gallery  comes  from  the  ground  of  the  adjacent  valley  and 
hills  and  not  from  the  river.  Moreover,  the  straining  process 
does  not  separate  the  bacteria.  After  several  years  of  operation 
of  the  filtering  gallery  at  Lawrence,  the  supply  not  only  dimin¬ 
ished  gradually,  but  the  quality  deteriorated  and  became  finally 
inferior  to  the  Merrimac  river  water,  a  greater  number  of  bacteria 
being  found  in  the  water  after  than  before  its  passage  through  the 
gallery. 

Air,  or  more  properly  oxygen  in  this  diluted  form,  is  nature’s 
great  scavenger.  What  escapes  the  ravenous  appetite  of  the  liv¬ 
ing  is  silently  destroyed  by  this  relentless  agent.  The  refuse  of 
the  laboratory  of  life  is  all  burnt. 

Oxygen  is  soluble  in  water  at  the  ordinary  temperature  and 
atmospheric  pressure,  in  the  proportion  of  about  in  volume, 
and  is  ever  at  work,  in  collaboration  with  the  fishes,  the  aquatic 
plants,  the  infusoria  and  the  bacteria,  on  the  dead  organic  matter 
carried  by  the  waters  of  lakes  and  streams. 

The  motion  of  the  water  enhances  its  action  by  rendering 
aeration  more  complete  and  bringing  in  closer  contact  the  oxygen 
and  organic  matter  ;  hence  the  beneficial  effect  of  waves,  rapids, 
cascades,  and  waterfalls.  So  effective  are  these  natural  means  of 
aeration  that  the  amount  of  oxygen  in  river  water  is  rarely  found 
to  vary  much,  unless  the  water  has  been  seriously  contaminated 
by  sewage. 

In  large  masses  of  stagnant  water,  such  as  are  found  in 
storage  reservoirs  of  great  capacity,  relatively  to  the  daily  draught 
made  from  them  the  case  is  different,  and  artificial  aeration  by 
weirs,  fountains  and  direct  injection  has  been  applied  with  good 
results.  Aeration  is  also  necessary  to  render  palatable,  boiled  or 
distilled  water. 

Unfortunately,  oxygen  does  not  destroy  the  bacteria ;  its 
action  is  auxiliary  to  theirs  in  perfecting  the  nitrification  of  the 
organic  matter  upon  which  they  feed.  Aeration  can,  therefore, 


—  8  — 

be  considered  only  as  a  useful  adjunct  to  a  complete  process  of 
purification,  but  insufficient  of  itself  to  accomplish  the  desired 
result. 

Since  the  discovery  of  Medlock,  forty  years  ago,  and  the 
researches  of  Bischof  and  Sir  Frederick  Abel,  it  has  been  known 
that  iron  rust  will  remove  a  large  proportion  of  the  organic  mat¬ 
ter  in  water.  It  has  also  been  shown  by  Dr.  Frankland  and  other 
experimenters  that  bacteria  can  to  a  very  large  extent  be  removed 
from  water  by  agitation  with  solids  in  a  fine  state  of  division. 
These  properties  have  been  utilized  in  Mr.  W.  Anderson’s  iron 
process  of  purification,  which  has  been  in  practical  operation  for 
ten  years  at  Antwerp,  and  on  a  large  experimental'  scale  at  the 
Lee  Bridge  works  of  the  Hast  London  Water  Company.  In  his 
experiments  on  agitation  with  solid  particles,  Dr.  Frankland  de¬ 
monstrated  that  the  separation  of  the  bacteria  from  the  water  was 
not  permanent ;  that  the  bacteria  were  not  destroyed  but  became 
attached  to  the  solid  matter  in  a  state  of  mechanical  suspension, 
and  settled  to  the  bottom.  That  their  vitality  was  not  impaired 
was  shown  by  the  fact  that  they  would  soon  rise  from  the  sediment 
and  diffuse  again  in  great  numbers  through  the  water. 

In  order  to  separate  the  bacteria  by  the  Anderson  process, 
sand  filtration  must  be  resorted  to,  as  practiced  at  Antwerp.  The 
process  of  itself  must  therefore  be  considered  only  as  a  useful — 
but  as  will  be  shown  hereafter — not  an  indispensable  auxiliary  to 
sand  filtration.  Its  principal  advantage  is  a  more  complete  re¬ 
moval  of  the  organic  matter  in  the  water.  From  ^3  to  ^  parts 
are  removed. 

The  various  methods  of  chemical  treatment  for  softening 
hard  water,  of  which  Dr.  Clark’s  lime  process  is  typical,  remove 
also  the  bacteria  in  a  manner  similar  to  that  of  the  Anderson 
process.  The  bacteria  become  attached  to  the  carbonate  precipi¬ 
tate  and  settle  down  with  it,  but  again  this  disappearance  is  but 
temporary ;  at  the  end  of  a  few  days  they  will  reappear  in  large 
numbers  unless  they  are  permanently  removed  with  the  precipitate 
by  filtration.  There  would  be  110  occasion  to  apply  such  a  pro¬ 
cess  to  the  Ohio  river  water,  which  is  reasonably  soft  even  at 
low  water  stages. 

Mechanical  filtration  is  done  in  closed  vessels,  under  pressure, 
and  at  a  rapid  rate ;  generally  with  the  addition  of  a  coagu- 
lent.  Suitable  appliances  are  used  to  wash  the  sand  at  frequent 
intervals  without  renewing  it. 


—  9  — 

This  system  has  found  favor  principally  in  America,  where 
many  patents  have  been  issued  for  various  forms  of  filters.  One 
of  the  first  in  date  is  the  Warren  filter,  invented  by  one  of  the 
owners’ of  a  paper-mill  at  Cumberland  Mills,  Maine,  and  applied 
there  in  1886  for  the  filtration  of  12,000,000  gallons  per  day.  •  It 
has  been  applied  since  to  a  large  number  of  paper-mills  and  to 
several  town  supplies,  aggregating  about  60,000,000  gallons  per 
day.  A  settling  basin  is  generally  used  to  remove  the  coarsest 
matter;  75  to  100  pounds  of  alum  to  1 ,000,000  ,;gallons  of  water 
is  used  as  a  coagulent.  The  sand  is  washed  with  filtered  water, 
the  frequency  of  washings  varying  with  the  degree  of  turbidity 
of  the  water.  From  2  to  5  per  cent,  of  the  filtered  water  is  said 
to  be  sufficient  for  the  purpose  of  washing.  The  cost  of  a  plant 
appears  to  be  about  $10,000  per  *1,000,000  gallons. 

The  purification  of  the  Platte  river  water,  for  the  supply  of 
Denver,  Colorado,  furnishes  another  example  of  mechanical  filtra¬ 
tion.  The  type  of  filters  employed  there  is  the  invention  of  the 
chief  engineer,  Mr.  C.  P.  Allen.  The  daily  output  is  10,000,000 
gallons. 

The  rate  of  filtration  in  mechanical  filters  is  from  3,000  to 
6,000  gallons  per  day  per  square  foot  of  filter,  which  is  from  50 
to  100  times  faster  than  the  rate  recommended  by  the  best 
authorities  for  gravity  filtration  on  tillering  beds.  Mechanical 
filtration  removes  practically  all  the  visible  suspended  matter  and 
about  one  half  of  the  organic  matter  in  the  water. 

No  systematic  biological  studies  have  yet  been  made  to  deter¬ 
mine  its  degree  of  efficiency  in  removing  bacteria,  but  from  the 
fact  that  satisfactory  results  in  this  respect  only  obtain  in  filtering 
beds,  with  a  comparatively  slow  and  a  very  uniform  rate  of  filtra¬ 
tion,  it  may  be  surmised  with  a  great  degree  of  probability  that 
bacterial  purification  by  this  process  must  be  very  incomplete. 

The  history  of  sand  filtration  is  interesting' in  showing  that 
in  his  efforts  to  imitate  nature  in  his  work,  the  engineer  may 
build  better  than  he  knows.  If  Mr.  Simpson  could  be  with  us 
to-night,  I  think  he  could  frankly  say  to  you  that  in  constructing 
the  first  filter  beds  for  the  London  companies,  he  had  110  other 
object  in  view  than  the  separation  of  the  solid  matter  which  gives 
a  turbid  appearance  to  the  Thames  water.  These  filter  beds  had 
been  in  use  for  a  generation,  contributing  their  part  to  the  excel¬ 
lent  sanitary  conditions  which  have  made  .London  one  of  the 


10- 


healthiest  cities  in  the  world,  before  it  was  discovered  that  the 
clarification  of  the  water  was  the  least  important  part  of  their 
function,  and  that  when  properly  operated  they  removed  in  a 
very  complete  manner  all  the  living  organisms  which  are  now 
known  or  suspected  to  be  man’s  worst  enemies. 

Dr.  Percy  Frankland  was,  I  think,  the  first  one  to  establish 
this  fact  in  a  conclusive  manner,  by  the  careful  analysis  which  he 
made  of  the  London  waters  in  1885  and  succeeding  years.  His 
first  experiments,  covering  a  period  of  four  months,  showed  the 
average  per  cent,  of  reduction  of  number  of  bacteria  by  filtration, 
for  five  of  the  London  companies,  to  be  98  per  cent.  The  daily 
quantity  of  water  filtered  by  the  companies  at  the  time  when  the 
experiments  were  made  was  70,500,000  gallons,  the  storage  capa¬ 
city  of  the  settling  reservoirs  516,000,000  gallons,  the  average  rate 
of  filtration  it7q  gallons  per  square  foot  per  hour,  the  average 
thickness  of  sand  in  the  filter  beds  3  feet  3  inches,  the  average 
per  centage  of  filter  beds  cleaned  per  month  74.  Dr.  Frankland 
ranks  as  follows  the  principal  factors  in  the  efficiency  of  the 
filter  beds : 

1st.  Storage  capacity  for  the  unfiltered  water. 

2d.  Thickness  of  sand  in  filter  bed. 

3d.  Rate  of  filtration. 

4th.  Frequency  of  cleaning. 

Dr.  Frankland’s  conclusions  are  confirmed  in  a  general  man¬ 
ner  by  Mr.  Gill  in  his  report  011  the  operation  of  the  filter  beds 
for  the  city  of  Berlin,  where  the  thickness  of  sand  averages  2  feet 
and  the  rate  of  filtration  3  gallons  per  square  foot  per  hour. 
Biological  examinations  of  the  water  at  the  filtering  station  were 
made  daily,  the  efficiency  in  removing  bacteria  was  found  to  vary 
from  88  per  cent,  to  99t7o  Per  cent.,  according  to  conditions  of  the 
beds  and  the  regularity  of  operations.  A  uniform  rate  of  filtration 
and  frequent  cleaning  of  the  beds  were  found  to  be  the  principal 
factors  of  efficiency. 

The  work  done  since  1887  under  the  auspices  of  the  Massa¬ 
chusetts  State  Board  of  Health  at  the  Lawrence  Experimental 
Station,  has  thrown  a  great  deal  of  light  on  the  subject,  and 
leaves  no  doubts  as  to  the  thoroughness  of  the  purification  effected 
by  this  method.  The  experiments  were  conducted  with  water 
from  the  Merrimac  river,  which  receives  the  sewage  of  Lowell 
about  nine  miles  above  the  Experimental  Station.  Briefly  stated, 


li¬ 


the  latest  results  and  conclusions  are  as  follows : 

For  rates  of  filtration  varying  from  one-half  to  three  million 
gallons  per  acre  per  twenty-four  hours,  the  number  of  bacteria 
escaping  through  the  filter  never  exceeded  of  i  per  cent. 

The  bacterial  efficiency  of  old  filters  in  1893  was  as  good  as 
in  1892. 

A  low  rate  of  filtration  is  safer  than  a  high  rate,  but  up  to  a 
certain  limit  the  rate  has  little  influence.  A  high  rate  of  efficiency 
was  obtained  with  the  rate  of  9,000,000  gallons  per  acre. 

It  is  of  great  importance  that  the  rate  be  uniform ,  and  that 
the  beds  be  filled  with  water  slowly  after  cleaning. 

Contrary  to  what  happens  for  the  filtration  of  sewage,  inter¬ 
mittent  and  continuous  methods  are  equally  effective,  which  is 
explained  by  the  presence  of  oxygen  in  river  water  and  its  absence 
from  sewage. 

The  proportion  of  albuminoid  ammonia  removed  averages 
55  per  cent. 

The  proportion  of  color  removed  averages  40  per  cent. 

Two  explanations  of  the  action  of  filter  beds  have  been  given  ; 
First:  that  of  Dr.  Koch  and  other  German  authorities,  which  at¬ 
tribute  the  principal  effect  to  a  surface  layer  of  slime,  the  action 
being  partly  mechanical  and  partly  biological.  According  to  this 
theory  a  shallow  depth  of  1  foot  only  of  fine  sand  would  be  useful. 
Second:  that  of  the  Massachusetts  State  Board  of  Health,  which 
considers  the  action  as  being  entirely  biological  and  due  to  aerobic 
bacteria  adhering  to  the  grains  of  sand.  This  theory  seems  to  be 
sustained  by  the  fact  that  a  greater  depth  of  sand  increases  the 
efficiency,  and  that  a  varying  rate  of  filtration,  which  would  tend 
to  detach  the  bacteria  from  the  sand,  decreases  it. 

The  example  of  London  and  Berlin  has  been  followed  by 
many  other  European  cities  who  now  filter  their  water  supplies. 
A  partial  list  of  them,  as  well  as  of  other  large  cities  which  do  not 
filter  their  water,  is  given  by  Mr.  Wm.  Hazen  in  the  paper  read 
by  him  on  November  21,  1894,  at  a  meeting  of  the  Boston  Society 
of  Civil  Engineers.  It  is  as  follows : 


— 12 


Filtered  River  Supplies. 


City. 

Popula¬ 

tion. 

Gallons  Daily, 

Source. 

total. 

Capita. 

Loudon  (7  companies) 

5,030,000 

190,000,000 

38 

Thames  and  Lea 

Berlin  . 

1,606,000 

26,000,000 

16 

Spree 

St.  Petersburg . 

960,000 

39,000,000 

40 

Neva 

Hamburg . 

583,000 

32,000,000 

53 

Elbe 

Warsaw . 

500,000 

6,000,000 

12 

Vistula 

Breslau . 

335,000 

7,000,000 

22 

Oder 

Rotterdam . 

240,000 

13,000,000 

54 

Mease  (Rhine) 

Magdeburg . 

200,000 

5,000,000 

24 

Elbe 

Filtered, 

Not  From  rivers. 

Amsterdam . 

515,000 

10,000,000 

20 

Dunes  and  Canal 

Liverpool . 

815,000 

22,000,000 

27 

Impounding  Reservoir 

Bradford . 

364,000 

r  2,000,000 

33 

Impounding  Reservoir 

Dublin . 

327,000 

18,000,000 

55 

Impounding  Reservoir 

Unfiltered  Ground  Water. 


Paris . 

Vienna . 

Buda  Pestli . 

London  (Kent  Co.) . 

Leipzic . 

Munich . 

Dresden  . 

Cologne . 

Frankfort . 

2,500,000 

1 ,000,000 
500,000 
460,000 
360,000 
300,000 
280,000 
255,000 
186,000 

J  53,000,000 
t  80,000,000 
23,000,000 
32,000,000 
•  1 6,000,000 
5,500,000 
1 1,500,000 
6,000,000 
1 1 ,500,000 
6,700,000 

21 

32 

23 

65 

35 

15 

38 

21 

45 

36 

Springs  (Domestic) 
Seine  (Public) 

Springs 

Wells  by  the  Danube 
Wells  in  Chalk 

Wells 

Springs 

Filter  Gallery 

Wells  by  Rhine 

Wells  and  Springs 

Unfiltered  Surface  Water. 

Manchester . 

963,000 

24,000,000 

24 

Impounding  Reservoir 

Glasgow . 

794,000 

50,000,000 

64 

Loch  Kathrine 

The  first  filter  beds  in  the  United  States  were  built  for  the 


town  of  Poughkeepsie  in  1870  by  J.  P.  Kirkwood,  after  a  voyage 
to  Europe  undertaken  for  the  special  purpose  of  studying  the 
results  of  sand  filtration. 

This  plant  remained,  I  believe,  for  a  number  of  years  as  the 
only  representative  of  its  kind  in  this  country,  until  the  publica¬ 
tion  of  the  Lawrence  experiments  had  again  drawn  the  attention 
of  engineers  to  the  merits  of  the  system.  Four  small  plants  have 
been  built  lately  at  Lawrence  and  Nantucket  in  Massachusetts 
and  at  Ilion  and  Hudson  in  New  York. 


A  practical  test  of  the  sanitary  effect  of  sand  filtration  is 
found  in  the  marked  decrease  of  the  death  rate,  which  has  in¬ 
variably  followed  its  introduction,  and  the  comparative  immunity 
of  cities  who  filter  their  water  supply,  from  epidemics  of  cholera 
and  typhoid  fever. 


9 


13 


Dr.  Billings  gave  a  striking  illustration  of  this  fact  in  his 
address  before  the  medical  society  of  the  District  of  Columbia 
October  24,  1894,  which  I  quote  for  the  benefit  of  those  who  may 
not  have  read  this  very  interesting  paper. 

“  Hamburg  and  Altona  form  one  continuous  building  area 
so  that  it  is  impossible  for  a  .stranger  to  see  any  difference  in  the 
character  of  the  buildings  or  the  surroundings.  *  *  * 

The  two  cities  are,  however,  quite  distinct  in  their  form  of  gov¬ 
ernment,  and  what  is  more  important  to  us,  in  their  water  supply. 
*  *  *  Hamburg  took  its  water  from  the  River  Elbe  above  the 

town,  though  not  above  tidal  influence,  and  supplied  it  unfiltered, 
while  Altona  took  its  water  from  the  same  river  below  the  town, 
where  it  was  highly  polluted  with  sewage,  but  filtered  it  through 
sand  filters  before  distributing  it  to  the  people. 

“In  the  great  cholera  outbreak  in  1892  the  cases  occurred 
almost  exclusively  in  Hamburg,  and  in  a  map  of  the  two  cities, 
on  which  the  cholera  cases  are  located  by  red  dots,  I  saw  the 
boundary  line  between  Hamburg  and  Altona  almost  as  distinctly 
marked  by  the  dots  as  if  it  had  been  shaded  in  for  that  purpose. 
It  is  true  that  there  were  cases  in  Altona,  but  inquiry  showed  that 
in  almost  all  these  cases  the  sick  had  either  drunk  Hamburg  water 
or  water  taken  directly  from  the  river. 

“One  of  the  most  remarkable  bits  of  evidence  is  furnished  by 
a  small  court,  the  houses  about  which  are  occupied  by  several 
hundred  people.  This  court  is  in  Hamburg,  on  the  boundary  line 
between  it  and  Altona,  but  for  some  reason  it  was  not  supplied 
with  water  from  the  Hamburg  works  but  from  those  of  Altona. 
Now  on  the  map  just  referred  to,  there  are  no  red  spots  on  this 
court,  although  they  surround  it  on  three  sides,  the  fourth,  or 
Altona  side,  being  free.” 

An  essential  condition  of  the  successful  operation  of  filtering 
plants,  is  that  they  should  be  properly  managed  and  cared  for. 
This  fact  is  now  fully  recognized  and  the  European  plants  referred 
to  are  all  placed  in  the  hands  of  able  engineers  and  under  constant 
bacteriological  inspection. 

The  large  area  ot  bottom  land  extending  for  several  miles 
along  the  north  shore  of  the  Ohio  river,  above  the  mouth  of  the 
Little  Miami,  affords  a  suitable  location  for  filter  beds,  and  the 
extensive  sand  bar's  which  line  the  northern  bank  of  the  river  in 
the  same  vicinity  would  permit  the  use  of  straining  cribs  such  as 
have  been  applied  lately  at  several  places  011  the  Allegheny  river. 


14  - 


The  preliminary  clarification  of  the  water  before  filtration 
is  generally  done  by  means  of  settling  basins.  If  the  same  result 
can  be  accomplished  by  straining  cribs,  a  large  saving  in  the  cost 
of  the  plant  would  be  realized.  With  a  sufficiency  of  duplicate 
machinery  the  storage  of  a  large  quantity  of  water  is  quite  un¬ 
necessary,  nor  is  it  even  desirable,  the  rapid  development  of 
bacteria  from  the  few  germs  that  would  always  escape  from  the 
filters,  making  it  almost  essential  that  the  water  be  consumed  as 
soon  as  possible  after  filtration.  The  restoration  of  the  Eden  park 
reservoir  and  its  adaptation  to  service  as  a  pure  water  basin  would 
be  all  the  outlay  required  in  the  way  of  storage. 

It  is  apparent  that  the  problem  of  a  pure  water  supply  can 
be  solved  by  the  City  of  Cincinnati  quite  within  her  means. 

The  question  may  be  asked,  Why  should  the  entire  water 
supply  of  the  city  be  filtered,  when  scarcely  one-third  is  used  for 
domestic  purposes?  It  does  seem  extravagant  to  furnish  filtered 
water  for  running  elevators  and  for  sprinkling  streets  and  lawns, 
but  it  would  probably  be  quite  as  expensive  to  provide* the  double 
system  of  mains  required  for  the  delivery  of  two  kinds  of  water. 
The  City  of  Paris  has  done  so;  with  her  it  was  not  a  matter  of 
choice  but  of  necessity.  Her  example  has  not  been  followed. 
Moreover,  beyond  the  question  of  economy,  there  are  good  reasons 
why  a  double  system  of  distribution  should  be  avoided,  ist.  There 
would  always  be  a  suspicious  liability  of  an  open  connection 
between  the  two  systems  of  conduits.  2nd.  Experience  shows 
that  many  people  will  drink  the  water  which  happens  to  be  the 
most  convenient,  regardless  of  consequences. 

This  last  objection  applies  with  equal  force  to  the  systems 
which  would  leave  the  purification  or  sterilization  of  drinking 
water  to  private  initiative,  each  family  and  establishment  solving 
the  problem  in  its  own  way,  or  buying  sterilized  water  from  some 
private  company  making  it  ^  business  to  furnish  it. 

Three  methods  of  private  treatment  have  been  proposed  and 
applied  on  a  more  or  less  extensive  scale.  The  one  more  gener¬ 
ally  used  is  filtration.  Innumerable  forms  of  filters  have  been 
invented  and  introduced  for  domestic  usage.  A  common  feature 
to  all  of  them  is  that  the  water  is  made  to  percolate  through  a 
porous  substance,  which  separates  all  the  solid  particles  which 
can  not  pass  through  its  pores.  The  particular  nature  of  this  fil¬ 
tering  medium  and  the  mechanical  arrangement  to  facilitate  clean- 


—  15  — 


in g  being  the  principal  points  of  differences.  Sponge,  mineral 
wool,  sand,  vegetable  and  animal  charcoal,  coke,  spongy  iron, 
sandstone,  pumice  stone,  biscuit  porcelain  and  other  artificial 
stones  have  been  used,  and  generally  yield  bright,  clear  water, 
agreeable  to  the  eye  and  to  the  taste.  The  separation  of  the  bac¬ 
teria  is  far  less  satisfactory,  as  has  been  shown  repeatedly  by 
careful  biological  examinations  made  at  different  times  and  places 
by  different  experimenters. 

The  experiments  of  Dr.  Percy  Frankland  with  6-inch  layers 
of  sand,  iron  sponges,  animal  and  vegetable  charcoal  and  coke, 
show,  that  while  with  a  slow  rate  of  filtration  the  separation  of 
the  bacteria  at  the  beginning  of  operations  is  almost  perfect,  the 
efficiency  gradually  deteriorates  with  time,  until,  if  the  experiment 
is  prolonged  sufficiently,  more  bacteria  are  found  in  the  water 
after  than  before  filtration.  The  experiments  made  at  Lawrence 
with  a  greater  depth  of  sand,  show,  however,  that  sand  filters,  if 
properl}"  constructed  and  operated,  may  preserve  an  efficiency  of 
99%  almost  indefinitely. 

The  Pasteur  filters,  made  of  biscuit  porcelain,  and  the  Berke- 
feld  filters,  made  of  baked  infusorial  earth,  are  admitted  to  be  the 
most  reliable.  They  yield  in  the  first  instance  sterile  water,  and 
will  continue  to  do  so  for  a  length  of  time,  varying  with  the 
quality  of  the  porcelain  and  the  character  of  the  water,  from  one 
to  four  weeks;  but  Frendereich’s  and  Nordtmeyer’s  experiments 
show  that  the  pores  of  the  porcelain  are  being  gradually  filled 
during  this  time  with  colonies  of  bacteria  that  will  finally  appear 
in  large  number  in  the  filtered  water.  The  safe  usage  of  these 
filters  require,  therefore,  that  they  should  be  carefully  washed  and 
sterilized  every  week.  The  conclusion  to  be  drawn  from  all  these 
facts  is,  that  whilst  domestic  filters  have  been  and  will  continue 
to  be  very  useful  appliances  when  operated  with  intelligent  care; 
their  efficiency  is  dependant  on  such  constant  attention  and  watch¬ 
fulness  that  they  are  not  a  safe  and  practicable  means  of  purifica¬ 
tion  in  the  hands  of  the  general  public. 

Boiling  and  distilling  have  also  been  suggested  for  the  steril¬ 
ization  of  drinking  water.  It  is  well  known  that  all  living  germs 
are  destroyed  at  the  temperature  of  boiling  water  under  ordinary 
atmospheric  pressure  maintained  for  15  or  20  minutes.  The 
practice  of  boiling  their  drinking  water  is  found  to  a  very  large 
extent  among  the  most  intelligent  part  of  communities  whose 


16  — 


water  supply  is  one  of  doubtful  purity;  of  late  years  it  has  come 
to  be  a  standing  rule  in  many  households  in  Cincinnati.  Distilled 
water  is  also  as  a  matter  of  course  sterile,  and  is  used  very  gener¬ 
ally  on  steamships  equipped  with  a  distilling  apparatus,  to  avoid 
the  necessity  of  carrying  a  large  supply  of  drinking  water — -always 
liable  to  deterioration  during  a  long  voyage. 

Theoretically,  boiled  and  distilled  water  should  always  be 
biologically  pure,  practically  they  are  rarely  so;  on  account  of  the 
precautions  necessary  to  preserve  their  initial  purity  being  .seldom' 
taken.  All  bacteriologists  agree  to  the  fact  that  bacteria  will  de¬ 
velop  almost  as  rapidly  in  boiled  and  distilled  water  as  they  would 
in  any  other.  The  introduction  of  a  few  colonies  in  the  stored 
water  would,  therefore,  suffice  to  populate  it  thoroughly  in  the 
course  of  a  few  days,  and  this  inoculation  is  extremely  difficult  to 
avoid,  especially  if  the  water  is  aerated  after  boiling,  as  it  .should 
be  to  make  it  palatable. 

The  principal  objection  to  these  methods  of  purification,  how¬ 
ever,  is  their  great  cost.  If  we  estimate  on  the  utilization  of 
10,000  heat  units  per  pound  of'coal  burnt  in  the  heaters — which  is 
probably  too  high — one  pound  of  coal  would  bring  about  66  pounds 
of  water  to  the  boiling  point  from  an  initial  temperature  of  6o°; 
i,ooo  gallons  would  therefore  require  i  x  i,ooox  =126  lbs.  of 
coal,  costing,  at  $1.75  per  ton  1  VVoV 6  —  $°- 1 1  • 

For  distilled  water;  estimating  on  the  most  improved  form 
of  apparatus,  where  the  heat  of  condensation  is  utilized  to  the 
utmost  limit  practicable,  the  cost  of  fuel  would  be  at  least  double, 
viz.:  22  cts.  per  1,000  gallons.  If  we  should  add  to  these  figures  the 
cost  of  aeration,  of  labor,  of  delivery,  of  repairs,  of  interest  on  cap¬ 
ital,  of  depreciation  of  plant,  &c.,  we  would  arrive  at  such  prices 
as  would  perhaps  be  paid  willingly  by  the  rich,  but  which  would 
be  prohibitor}r  for  the  great  mass  of  the  population,  where  the  lib¬ 
eral  use  of  water  should  be  specially  encouraged  and  wholesome 
water  made  a  cheap  luxury.  The  only  practical  solution  of  the 
problem  seems  to  be  the  purification  of  the  entire  city  supply  by 
sand  filtration. 


